Post-agricultural succession in the fallow swiddens of Southeastern Brazil

Abstract

Agricultural practices have been occurring for centuries in the Brazilian Atlantic Rain Forest, which contains one of the highest levels of biodiversity in the world. The communities that still practice traditional shifting agriculture are constrained by legal, economic and social factors, which makes the practice of itinerant agriculture a complex dynamic process. The long-term effect of repeated, long-fallow shifting cultivation on plant communities in secondary forest fallows of various age and slash-and-burn history was examined in a quilombola village in Southeastern Brazil. We carried out vegetation surveys in 12 sites, ten in areas of shifting cultivation and two in secondary forests formed after natural disturbances. We chose three age groups for sampling, i.e., post-harvest fallow or post-disruption times for natural areas. The fallow period after cultivation ensures the continuous recovery of the composition and structure of vegetation, but even after five decades the alpha and beta diversities had not reached the values observed in mature forests. The number of species and basal area increased over time but the differences between areas in the same age group were as large as between age groups. The two disturbed natural areas had lower richness than the fallow swiddens of the same age. The data suggest that the intensive extraction of non-timber forest products to supply the market, and therefore extraneous to traditional activity, has negatively affected the sustainability of the system. Actions to recover stocks of these forest products together with integrated management and input of resources can maintain the sustainability of the system.